Composition for chemical mechanical planarization of copper, tantalum and tantalum nitride

ABSTRACT

Chemical mechanical planarization or spin etch planarization of surfaces of copper, tantalum and tantalum nitride is accomplished by means of the chemical formulations of the present invention. The chemical formulations may optionally include abrasive particles and which may be chemically reactive or inert. Contact or non-contact CMP may be performed with the present chemical formulations. Substantially 1:1 removal rate selectivity for Cu and Ta/TaN is achieved.

RELATED APPLICATIONS

[0001] The present application is filed pursuant to 37 C.F.R. § 1.53(b)as a continuation-in-part of application Ser. No. 09/357,264, filed Jul.19, 1999, and claims priority therefrom as to subject matter commonlydisclosed pursuant to 35 U.S.C § 120 and 37 C.F.R. § 1.78.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] This invention relates to chemical mechanical processes for theplanarization of surfaces, and to chemical compositions especiallysuited thereto. More particularly, this invention relates to compositionfor the chemical mechanical planarization of conductive, barrier anddielectric surfaces as typically encountered in the fabrication ofintegrated circuits, including compositions specifically formulated forCMP and non-contact chemical planarization of Cu/Ta/TaN are

[0004] 2. Description of Related Art

[0005] Fabrication of integrated circuits (“ICs”) to improve performanceand reduce costs involves complex analysis of materials properties,processing technology and IC design. IC's consist of multiple layers ofconducting, insulating and semiconductor materials, interconnected invarious ways by conducting metallic channels and plugs (“vias”),including various dopants implanted into various materials for producingthe electronic functionality desired of the IC. The near-universal trendin the manufacture of integrated circuits is to increase the density ofcomponents fabricated onto a given area of wafer, increase theperformance and reliability of the ICs, and to manufacture the ICs atlower cost with less waste and fewer defective products generated by themanufacturing process. These goals lead to more stringent geometric anddimensional requirements in the manufacturing process. In particular,etching precise patterns into a layer is facilitated by the layer havinga surface as nearly planar as feasible at the start of the patterningprocess. For the common case of patterning by means of photolithography,a planar surface permits more precise location and dimensioning forfocusing the incident radiation onto the surface to be etched than wouldbe possible with a surface having deviations from planarity. Similarconclusions typically apply for electron beam or other means of etching.That is, deviations from planarity of the surface to be etched reducethe ability of the surface to support precisely positioned and preciselydimensioned etches. In the following description of the presentinvention we focus on the typical etching, planarization andphotolithography processes as practiced in the manufacture of ICs.However, this is by way of illustration and not limitation, as thoseskilled in the art of etching will appreciate that the techniques of thepresent invention for producing planar surfaces will have applicabilityin increasing the precision of etching by means other thanphotolithography. In addition, the present invention is not limited tothe field of IC manufacture and may find applicability in other areas oftechnology requiring planar surfaces.

[0006] Chemical Mechanical Planarization (“CMP”) has been successfullyintegrated into integrated circuit multilayer manufacturing processes toachieve highly planar surfaces as described in text books (for example,“Microchip Fabrication” by Peter Van Zant, 3rd Ed., 1997 and “ChemicalMechanical Planarization of Microelectronic Materials” by J. H.Steigerwald, S. P. Murarka and R. J. Gutman, 1997) and generally knownin the art. We note that “CMP” is also used in the art to denote“Chemical Mechanical Polishing” as well as “Chemical MechanicalPlanarization”. We use CMP herein synonymously in either sense withoutdistinction.

[0007] A typical CMP process is depicted schematically in FIG. 1. Duringa CMP process, the wafer, 1, is typically held inside a rotating carrierand pressed onto a rotating pad, 2, under pressure, 6, while an abrasiveslurry, 5, (typically containing particles of abrasive such as SiO₂,Al₂O₃, and the like) flows between the wafer and the pad. The slurry, 5,will typically contain reagents for chemically etching the wafer, 1,leading to chemical as well as mechanical removal of material. Thus, inthe typical practice of CMP, material removal is effected by acombination of chemical attack and mechanical abrasion.

[0008] Typically, the wafer, 1, will be caused to rotate as depicted by3 in FIG. 1, while the polishing pad will itself rotate (4 in FIG. 1).FIG. 1 depicts the polishing pad and wafer rotating in the samedirection (for example, clockwise when viewed from above as in FIG. 1).However, this is merely for purposes of illustration andcounter-rotation of wafer and polishing pad is also practiced. Inaddition to the rotation of the wafer depicted by 3 in FIG. 1, thewafer, 1, may be caused to oscillate in the plane of the surface beingpolished, substantially perpendicular to the direction of the appliedforce, 6 (This oscillatory motion is not depicted in FIG. 1).

[0009] Recent work has indicated the ability to planarize surfaces bypurely chemical means, without the need for a polishing pad ormechanical contact with the surface undergoing planarization (Ser. No.09/356,487, incorporated herein by reference). As described in thereferenced application, appropriate etchant chemicals are applied to aspinning wafer under conditions and in such a fashion as to planarizethe wafer surface. The techniques described in Ser. No. 09/356,487 arecollectively denoted as “spin etch planarization” or SHP. Chemicalcompositions presented in the present application may be employed in SHPprocesses for the planarization of Cu/Ta/TaN surfaces as well as in moreconventional CMP

[0010] Increasing the speed and performance of ICs typically calls forincreasing the density of components on the wafer and increasing thespeed at which the IC performs its desired functions. Increasingcomponent density typically requires decreasing the size of conductingchannels and vias (or plugs). It is well known that decreasing thecross-section of a current-carrying conductor increases the electricalresistance of the conductor for the same material. Thus, decreasingcomponent size on ICs increases electrical resistance, degradingperformance and perhaps leading to unacceptable heating. This is onereason IC developers have been looking for conducting materials for usein IC fabrication having lower electrical resistance. Present ICtechnology typically makes use of tungsten (chemical symbol W) andaluminum (Al) as conductors. Both have adequate electricalconductivities in present devices, but future generations of IC deviceswill preferably make use of yet higher conductivity materials. Copper(Cu) is among the leading candidates.

[0011] Increasing the density of IC components on the wafer alsoincreases the capacitance of the circuits. That is, bringing chargecarrying circuit elements closer together increases the capacitivecoupling between such circuit elements. Higher capacitance isdetrimental to circuit performance, especially for higher frequencyoperation as would typically be encountered in telecommunicationapplications and elsewhere. However, capacitive coupling betweenproximate circuit elements can be reduced by reducing the dielectricconstant of the insulator or insulating material separating the coupledcircuit elements. Thus, in addition to seeking conductors with higherconductivities, insulators with lower dielectric constant (“low k”) arealso being sought for use as insulating layers in ICs.

[0012] Current multi-layer IC fabrication typically makes use oftungsten (W) CMP processes at each successive circuit level. Typically,blanket films of W, Titanium (Ti) and Titanium Nitride (TiN) aredeposited. The films are then typically polished, thereby removingmaterial resulting in (for example) W vias or “plugs” which are inlaid,typically in an SiO₂ dielectric layer. The W plugs act as electricallyconducting paths between the metal lines of adjacent layers of the IC.Typically, the metal lines connected by W vias will consists of alloysof Al and Cu in present ICs. In typical present IC designs, Ti and TiNlayers are used as barrier layers (to hinder unwanted diffusiveintermixing of components during fabrication) and adhesion layers (topromote good bonding between otherwise poorly bound layers and avoiddelamination). Such barrier and adhesion layers must also be removedduring W CMP to reveal the inlaid W plugs. Desirable CMP for such ICsshould remove the various layers equally and, thus, planarize in one CMPstep. Commercially available W slurries can achieve almost the ideal 1:1removal rate selectivity between W and Ti/TiN layers. This results in avery flat surface of the device wafers after W CMP. Thus, if othercombinations of conductor and insulators are to be used in ICfabrication, adequate chemical reagents for CMP must be employed andadequate planarization processes must be used. Such are among theobjects of the present invention.

[0013] The use of W vias, Al—Cu lines, and SiO₂ dielectric layers,although quite successful in present ICs, has inherent drawbacks thathinder attaining the circuit performance desired in future devices. TheAl—Cu alloys and W vias are conductive, but less so than Cu. The SiO₂dielectric layers (although good electrical insulators) have arelatively high dielectric constant, leading to deleterious capacitiveeffects. (“High k” typically denotes dielectric constants in the rangeof approximately 3 to 9.) The combination of relatively high resistivitymetals and relatively high dielectric constant insulators reducescircuit speed and reliability, particularly as the device geometry isreduced in future ICs below approximately 0.25 μm, (that is 0.25microns).

[0014] Metallic copper (Cu) has a lower resistivity than W or Al—Cualloys. Therefore, Cu is becoming a popular choice for the interconnectmetal to be used in future generation ICs. It is further envisioned thatlow k dielectric materials (that is, materials with dielectricconstants, k, less than about 3.0) will be used in conjunction with Cumetallization to reduce capacitive effects. However, both of thesechoices bring accompanying challenges in the fabrication of highperformance, low cost, reliable ICs. Low k dielectrics are oftenmechanically weak relative to conventional dielectrics and tend todelaminate under the stress of CMP, especially if the applied pressure,6, in FIG. 1 must be rather large in order to achieve adequate materialremoval rates. An adequate rate of material removal is required in orderto achieve planarization in an acceptable period of time. Addressingthese challenges, the focus of the present invention is on the use ofcopper, on barrier layers to avoid harmful diffusion of Cu, and slurrycompositions for effective Cu CMP (or SHP) in the presence of effectivebarrier and adhesion layers. Typical barrier layers in copper damasceneor dual damascene fabrication processes include Ta and TaN.

[0015] In order to increase performance and reduce manufacturing costs,it is envisioned that Cu metal will most likely be used in future ICs infabricating the metallic conducting channels within a layer and in thevias which connect adjacent layers. This will likely be accomplishedusing a “metal damascene” or “dual damascene” manufacturing approach.Damascene processing typically proceeds by depositing a blanket layer ofmetal on top of a patterned insulating or dielectric layer, therebyfilling channels and vias in the patterned insulating layer. Whennecessary, the metal deposition is preceded by the deposit of a barrieror adhesion layer between the metal and the dielectric. Since trench andvial filling is not typically uniform, the metal is deposited to fillthe features and covers the field regions between features as well. Thisblanket metal overlayer is then typically removed by CMP or etchingrevealing the inlaid metal channels and vias with a surface ideallycoplanar with the field regions of the surrounding dielectric. Thebarrier layer on the field region is also typically removed in theplanarization step. Dual damascene is a two-step damascene process,typically forming more than one layer of features in the dielectricbefore barrier layer and metal is deposited.

[0016] It is envisioned that the metal of choice for the nextgenerations of ICs will be copper. Therefore, to be concrete in ourdescription, we will describe the practice of the present invention inconnection with copper damascene or dual damascene processing includingthe use of Ta/TaN barrier layers. However, the present invention is notinherently so limited and other embodiments will be obvious to thosehaving ordinary skills in the art.

[0017] Copper has the advantage of higher conductivity, but suffers fromseveral complications which heretofore have delayed its adoption in ICs.Among copper's disadvantages is the fact that it is a very diffusivecontaminant. That is, copper diffuses widely and easily through othermaterials typically used in the fabrication of ICs, seriously degradingelectronic performance by doing so. It is among the objects of thepresent invention to address, eliminate or ameliorate some of theseattendant drawbacks in the use of Cu metallization in the fabrication ofICs.

[0018] In addition to its high rate of diffusion, reaction products ofcopper with typical etching reagents have often resulted in non-volatile(or insoluble) reaction products. Thus, etching of Cu with conventionCMP slurries has been difficult. Identification of a group of effectivecopper etching reagents having volatile or soluble reaction products(while maintaining adequate removal rate and selectivity) is among theobjectives of the present invention.

[0019] Tantalum (Ta) and Tantalum Nitride (TaN) have been identified aspromising barrier layer, or “liner metals”, that will prevent harmful Cudiffusion. Because CMP is presently the most effective and wellunderstood planarization technique, it is the natural method with whichto undertake the planarization of Cu, Ta or TaN. Such Cu/Ta/TaN CMPrequires slurries with high. Cu and Ta/TaN removal rates and close to a1:1 removal selectivity between Cu and the liner metals. However, Ta andTaN are mechanically hard and they do not react readily with mostetching chemicals. For these reasons, CMP slurries having appropriatechemical formulations to obtain 1:1 selectivity between Cu and the linermetals have been difficult to achieve. Hence, at present there is noslurry commercially available for Cu CMP.

[0020] Typical experimental Cu slurries are composed of H₂O₂, variousoxidizers, alumina and/or silica abrasive, and other chemicalcomponents, typically in acidic (low pH) solutions. (Tytgat et. aL. U.S.Pat. Nos. 4,981,553; 5,098,571). These formulations typically give goodCu removal rate, but often achieve very low Ta/TaN removal rates, evenwhen high polishing pressures are employed. Currently there are twocommon experimental approaches being employed for Cu CMP, both of whichsuffer from disadvantages. In one approach (Brusic, “A Cautious Approachto the Removal of Ta in the CMP Polishing of Cu/Ta Structures, 193^(rd)Electrochemical Society Meeting, May 1998) Cu CMP is conducted by usinga two-step polishing process to remove Cu and Ta/TaN. The Cu and Ta/TaNlayers are removed separately in sequence using two distinct slurries.This two step approach significantly complicates the fabricationprocesses and increases the cost of the CMP process applied to Cu. Asingle-step Cu CMP would be preferable, but it would require a slurrywith 1:1 selectivity for Cu and Ta/TaN. One possible way to increase theremoval rate of Ta/TaN layers is to dramatically increase the polishingdownforce. However, a higher polishing downforce is contraindicatedsince it could damage the underlying low k materials, which are oftenmechanically weak and subject to delamination. Achieving a slurry withthe required near 1:1 selectivity without the application of largepolishing downforce is among the objects of the present invention.

[0021] Slurry formulations that react chemically with inert liner metalsto achieve adequate removal rates and selectivity would be animprovement in Cu CMP. A single-step Cu CMP employing a slurry thatprovide 1:1 selectivity and high material removal rates at low polishingpressures, is highly desirable. However, a two-step CMP slurry that didnot require high polishing pressures, though less desirable than thesingle-step slurry, would still be an improvement in the present art.

[0022] The present invention is described for the specific example ofCMP slurries for Cu/Ta/TaN on IC wafers as this specific case isexpected to be a primary area of applicability of the present invention.However, the compositions and processes of the present invention are notinherently limited to these particular instances. The present inventioncould be useful for processing many different types of metallic,dielectric, or organic layers, or mixtures and/or composites thereof, onnumerous types substrate for numerous technical applications, as wouldbe known to those skilled in the art. In addition, etchant formulationsthat may be used in connection with non-contact CMP (or SHP) aredescribed.

BRIEF SUMMARY OF THE INVENTION

[0023] Chemical mechanical planarization of surfaces of copper, tantalumand tantalum nitride is accomplished by means of the chemicalformulations of the present invention. The chemical formulations mayoptionally include abrasive particles and which may be chemicallyreactive or inert. Contact or non-contact CMP may be performed with thepresent chemical formulations. Substantially 1:1 removal rateselectivity for Cu and Ta/TaN is achieved. In addition to 1:1 removalrate selectivity, the present invention provides adequate materialremoval rates without excessive downforce being necessary on (oftendelicate) low dielectric components. Etchant formulations of the presentinvention are also applicable for use with spin etch planarization.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE INVENTION

[0024]FIG. 1: Schematic depiction of Chemical Mechanical Planarization(“CMP”).

DETAILED DESCRIPTION OF THE INVENTION

[0025] In the following description and figures, similar referencenumbers are used to identify similar elements. For economy of languagewe use “CMP” to denote both chemical mechanical planarization in which apolishing pad is used (“contact CMP”) as well as non-contact CMP inwhich no polishing pad is used. SHP is included within this usage of CMPas a type of non-contact CMP.

[0026] The Cu/Ta/TaN CMP slurries, or “etchants”, described herein areimproved formulations of chemicals typically used for CMP includingabrasive slurries, metal etchants and cleaners, chemical polishes,brighteners, and pickling solutions, etc. Conventional (contact) CMPtypically includes abrasive particles in the etchant formulation,abrasives are typically not present in non-contact CMP. Etchants withand without abrasive particles are within the scope of the presentinvention. The chemical compositions of the etchant include chemicalmixtures, typically comprised of one or more of the followingconstituents: TABLE A Abrasive Particles Mineral Acids Organic AcidsStrong Bases Mineral Salts Organic Salts pH buffers Oxidizing AgentsOrganic and Inorganic Peroxides Corrosion Inhibitors Chelating AgentsSurface Modifying Agents Liquid polymers Surfactants SolutionStabilizers Solvents (including water)

[0027] In general, CMP use of the etchants described herein requires amethod of introducing the etchant onto the wafer surface and preferablya method for transporting the etchant across the wafer surface. Thepolishing pad and process depicted in FIG. 1 is the typical mechanismused in contact CMP. However, the CMP chemical formulations of thepresent invention need not include abrasives in the etchant mixture anddo not necessarily require mechanical contact between the wafer surfaceand another surface or body, such as a polishing pad. Thus, the etchantsof the present invention may be used to good effect in both contact andnon-contact CMP, but require different transport mechanisms (such asSHP) than the polishing pad depicted in FIG. 1.

[0028] In addition to adjusting the type and concentration of etchantconstituents, heating the etchant solution may be used to control theremoval and rate of removal of material from the surface of the wafer.Temperature control of the reaction may be achieved by introducing theetchant onto the wafer preheated to the desired temperature, by heatingthe polishing pad other body and/or by maintaining the polishing at aconstant temperature.

[0029] Improved CMP is achieved by means of etching solutions asdescribed below. Abrasive particles are optionally included and mayoptionally react with the surface of the wafer being etched as well asprovide mechanical removal of wafer material. Many suitable abrasivematerials could be used, including conventional abrasives (SiO₂, Al₂O₃and the like), and various nonconventional abrasives that are comprisedof metals, solid elemental particles (for example carbon), polymerparticles, oxides, carbides, fluorides, carbonates, borides, nitrides,or hydroxides of several metals, including, but not limited to, Al, Ag,Au, Ca, Ce, Cr, Cu, Fe, Gd, Ge, La, In, Hf, Mn, Mg, Ni, Nd, Pb, Pt, P,Sb, Sc, Sn, Tb, Ti, Ta, Th, Y, W, Zn, Zr, or mixtures thereof. Theseparticles may be coated with a thin layer of another material, includingbut not limited to those described above. The potential advantages ofthe use of coated particles are expected to include decreasing cost bycoating a less dense, inactive and inexpensive particle, such as SiO₂,with a chemically active, and often more dense and expensive activematerial such as CeO₂. The effective density of such particles will beless than solid particles comprising all chemically reactive material,and thus more stable in terms of particle settling according to StokesLaw which predicts a larger settling velocity for particles having ahigher density. Similarly for a given wt % of solids, slurries comprisedof coated abrasive particles (typically less dense) will have a greaternumber of particles in a given volume of fluid and thereby present agreater abrasive surface area in contact with the wafer surface.

[0030] It is envisioned in the practice of the present invention thatmany of the particle systems described herein will be produced by meansof the “sol” method. This typically involves growing the particles totheir final size in solution. By growing the particles entirely insolution and remaining in solution for use (that is, never dried) thereis no sintering or “necking” of the particles that will result in largeagglomerate, which may be damaging to the sensitive IC layers, orunderlying structures. Having avoided agglomeration, these particles areintroduced into solvent systems very readily and at lower cost thanconventional abrasives that typically must undergo additional andexpensive particle size reduction and powder dispersion processing. Thepractice of the present invention makes use of several particle sizedistributions. A bi-modal particle size distribution, or a multi-modalparticle size distribution, or a broad Gaussian particle sizedistribution, may all be employed in the practice of the presentinvention with typical particle sizes in the range 4 nm to 5 μm. It isenvisioned in the practice of the present invention that particle sizesgreater than approximately 5 μm will not give satisfactory results,particularly in terms of increasing removal rates and reducing defectsand scratches.

[0031] We note elsewhere herein typical components of the etchingreagents useful in the practice of the present invention. Practicalindustrial applications may also require the reagent mixture to containother additives to inhibit premature reaction, stabilize the mixture,increase shelf life of the reagent mixture, reduce volatility, inhibittoxicity, inhibit photodegradation, and the like. Such additives areknown to those skilled in the art and art not otherwise specified indetail herein.

[0032] Tables 1-13 following are examples of reagent mixtures usefullyemployed in the practice of the present invention for planarizing coppersurfaces or other surfaces as indicated on the Tables. TABLE 1 AQUEOUSPEROXIDE - PHOSPHORIC ACID REAGENT SOLUTIONS FOR PLANARIZATION OF COPPEROxidizer Co-Reactant Other Additives a) H₂O₂ H₃PO₄ HCl, aliphaticalcohols b) H₂O₂ H₃PO₄ HCl, Agidol (butylated hydroxytoluene) c) H₂O₂H₃PO₄ HCl, Agidol-2, d) H₂O₂ H₃PO₄ HCl, 2,6-di-tert-butyl-4[(dimethylamino) methyl]phenol e) H₂O₂ H₃PO₄ HCl; H₃PO₄, (HPO₄)²⁻, PO₄³⁻ f) H₂O₂ H₃PO₄ HCl, 2,6-di-tert- −4N,N-dimethyl aminomethyiphenol g)H₂O₂ H₃PO₄ borax h) H₂O₂ H₃PO₄ various additives

[0033] TABLE 2 AQUEOUS PEROXIDE - SULFURIC ACID REAGENT SOLUTIONS FORPLANARIZATION OF COPPER Oxidizer Co-Reactant Other Additives a) H₂O₂H₂SO₄/H₃PO₄ Ethylene glycol, ZnSO₄ b) H₂O₂ H₂SO₄ MeOH, Poly(oxyethylene)lauryl ether, Malic acid c) H₂O₂ H₂SO₄ HOOC(CX₂)_(n)COOH withX═OH, amine, H n = 1 − 4 d) H₂O₂ H₂SO₄ 3% tartaric acid 1% ethyleneglycol c) H₂O₂ H₂SO₄ 1,2,4-triazole, 1,2,3-triazole, tetrazole, nonionicsurfactant f) H₂O₂ H₂SO₄ C₂H₅OH, aliphatic alcohols, nonionic surfactantg) H₂O₂ H₂SO₄ Triflouroethanol, Laprol 602 ® surfactant, aliphaticalcohols h) H₂O₂ H₂SO₄ aliphatic alcohols i) H₂O₂ H₂SO₄ SiF₆, Organicsalt surfactant j) H₂O₂ H₂SO₄ various additives

[0034] TABLE 3 AQUEOUS PEROXIDE MINERAL ACID REAGENT SOLUTIONS FORPLANARIZATION OF COPPER Oxidizer Co-Reactant Other Additives a) H₂O₂HNO₃ alcohols, HOOC(CX₂)_(n)COOH X═OH, amines, H n = 1 − 4 b) H₂O₂ HNO₃various additives

[0035] TABLE 4 AQUEOUS NITRIC ACID REAGENT SOLUTIONS FOR PLANARIZATIONOF COPPER Oxidizer Co-Reactant Other Additives a) H₂O₂/HNO₃ H₃PO₄methanol b) H₂O₂/HNO₃ Triflouroethanol, Laprol 602 ® Surfactant,aliphatic alcohols c) HNO₃ H₃PO₄ PVA d) HNO₃ H₂SO₄ diphenylsulfamicacid, aliphatic alcohols e) HNO₃ H₂SO₄ HCl f) HNO₃ H₂SO₄ variousadditives g) HNO₃ BTA (benzotriazole)

[0036] TABLE 5 AQUEOUS PEROXIDE ORGANIC ACID REAGENT SOLUTIONS FORPLANARIZATION OF COPPER Oxidizer Co-Reactant Other Additives a) H₂O₂Oxalic acid Sodium oxalate, Benzotriazole, Sodium Lignosulfonate b) H₂O₂other organic various additives acids

[0037] TABLE 6 AQUEOUS DILUTE MINERAL ACID REAGENT SOLUTIONS FORPLANARIZATION OF COPPER Acid Other Additives a) H₃PO₄ various additives

[0038] TABLE 7 AQUEOUS CONCENTRATED ACID REAGENT SOLUTIONS FORPLANARIZATION OF COPPER Oxidizer Acids Other Additives a) H₃PO₄/Acetic/H₂SO₄ b) H₃PO₄/Acetic/HNO₃ c) H₃PO₄/Acetic/HNO₃/H₂SO₄ Glycol, GelatineCarboxymethyl- cellulous, amines, surfactants, heavy metal saltsincluding Cu and Ta. d) H₂O₂ H₃PO₄/Acetic/H₂SO₄ Glycol, GelatineCarboxymethyl- cellulous, amines, surfactants, heavy metal saltsincluding Cu and Ta. e) H₂O₂ H₃PO₄/H₂SO₄ 100 ml propylene glycol, 100 ml2-ethyl- hexylamine, 25 ppm Cl⁻. f) H₃PO₄/Acetic/HNO₃ nonionicsurfactant g) H₂O₂ H₃PO₄/Acetic/HNO₃/H₂SO₄ various additives h)H₃PO₄/HNO₃

[0039] TABLE 8 AQUEOUS DILUTE ACID - METAL SALT REAGENT SOLUTIONS FORPLANARIZATION OF COPPER Oxidizer Acid Metal Salt Other Additives a) HClCuCl b) HCl CuCl KCl c) HCl FeCl various additives d) H₂O₂ H₂SO₄ CuCln-propanol e) HCl CuCl various additives f) H₂O₂ H₂SO₄ CuCl variousadditives g) HCl FeCl₃ glycerol h) HNO₃ HCl FeCl₃ i) HCl FeCl₃ j) HClFeCl₃ various additives k) HCl FeCl₃ CuCl₂, SnCl₂ l) HCl FeCl₃ ethanol

[0040] TABLE 9 AQUEOUS OXIDIZER - SALT REAGENT SOLUTIONS FORPLANARIZATION OF COPPER Oxidizer 2nd Oxidizer Base Salt Other Additivesa) NaClO₃ NH₄F CuSO₄ Na EDTA salt of wetting agent b) FeNO₃ variousadditives c) (NT₄)₂S₂O₈ various additives d) CuNH₄Cl₃ NH₄OH variousadditives e) Na₂S₂O₃ K₂S₂O₅ various additives

[0041] TABLE 10 AQUEOUS BASE REAGENT SOLUTIONS FOR PLANARIZATION OFCOPPER Base Oxidizer Other Additives a) NH₄OH/KOH H₂O₂ various additivesb) NH₄OH H₂O₂ various additives c) NH₄OH (NH₄)₂S₂O₈ various additives d)NH₄OH Cu(NO₃)₂

[0042] TABLE 11 AQEUOUS ACID REAGENT SOLUTIONS FOR PLANARIZATION OFTANTALUM AND COPPER Oxidizer Acid Other Additives a) HNO₃ HF variousadditives b) H₂O₂ HF various additives c) HNO₃ HF lactic acid, variousadditives d) H₂O₂ HF H₂SO₄

[0043] TABLE 12 AQUEOUS BASE REAGENT SOLUTIONS FOR PLANARIZATION OFTANTALUM AND COPPER Base Acid Other Additives a) NaOH b) NaOH H₂O₂ c)KOH H₂O₂ d) NH₄OH H₂O₂

[0044] Remove oxide film after CMP with rinse of dilute acetic acid,dilute nitric acid, aqueous solution or other solutions. TABLE 13MISCELLANEOUS REAGENTS FOR PLANARIZATIONS OF COPPER a) EDTA, NH₄OH,H₂O₂, in aqueous solution b) Citric acid, Erythotbic acid,Triethanolamine, in aqueous solution c) Trisodium citrate,Triethanolamine, Sodium nitrate, in aqueous solution d) H₂SO₄, H₂O₂,Sodium molybdate, Phenosulfonic acid, in aqueous solution e) Mineralacid (sulfuric, HCl or the like), molybdenum salt

[0045] In addition to the additives shown in Tables 1-13 above, otheradditives include but are not limited to the following:

[0046] borax, zinc sulfate, copper carbonate, alcohol (including lowmolecular weight alcohols, glycols, phenols, aliphatic alcohols,polyvinylalcohols and the like), surfactants (including anionic,cationic, nonionic surfactants and others preferentially adhering tocertain materials, modifying thereby the chemical reactivity of certainsites), solution stabilizers (including polyvinyl alcohols and otheragents inhibiting spontaneous decomposition of oxidizing agents),wetting agents.

[0047] For example, one specific formulation uses highly concentratedH₂O₂ in a strong base, such as KOH, plus chemical-active abrasiveparticles such as CeO₂ or SnO₂, in conjunction with other chemicalcomponents. According to Tytgat (U.S. Pat. No. 4,981,553), the chemicaletchant alone (without abrasion) provides a Ta removal rate ofapproximately 1000-2000 Ångstrom/min., which is significantly higherthan Ta removal rates typically available Cu slurries. The presentinvention may be expected to achieve increased Ta removal rates in CMPby employing the additional mechanism of mechanical abrasion of thewafer by abrasive particles. In addition, heating the slurry, or theopposing body or pad, could enhance the removal rate of the Ta or TaNlayers. Thus temperature control may be another means of achieving a lowpolishing pressure CMP process.

EXAMPLES Example A

[0048] 50 parts by volume H₃PO₄

[0049] 40 parts by volume Acetic Acid

[0050] 10 parts by volume HNO₃

[0051] All acids are fully concentrated aqueous solutions.

[0052] The formulation of Example A yields a Cu removal rate ofapproximately 15,000 Å/min. when SEP is performed and a surfaceroughness (RMS) less than approximately 100 Å

Example B

[0053] 70 parts by volume H₃PO₄

[0054] 24 parts by volume Acetic Acid

[0055] 6 parts by volume HNO₃

[0056] All acids are fully concentrated aqueous solutions.

[0057] The formulation of Example B yields a Cu removal rate ofapproximately 152000 Å/min. when SEP is performed.

Example C

[0058] 50 parts by volume H₃PO₄

[0059] 40 parts by volume Acetic Acid

[0060] 3 parts-10 parts by volume HNO₃

[0061] All acids are fully concentrated aqueous solutions.

[0062] The formulation of Example C yields a Cu removal rate in therange from approximately 3,000 Å/min to approximately 20,000 Å/min. whenSEP is performed. The rate of Cu removal is approximately proportionalto the nitric acid content.

Example D

[0063] 50 parts by volume H₃PO₄

[0064] 40 parts by volume Acetic Acid

[0065] 3 to 10 parts by volume HNO₃

[0066] 1 to 15 parts by volune HF

[0067] All acids are fully concentrated aqueous solution.

[0068] The formulation of Example D provides simultaneous removal of Cuand layers of silicon-containing polymer or silicon-containing inorganic(such as TEOS (tetraethoxysilane) and silicon).

Example E

[0069] 42% by volume sulfuric acid

[0070] 8% by volume nitric acid

[0071] 0.5% by volume hydrochloric acid

[0072] remainder is water

[0073] All acids are fully concentrated aqueous solution

[0074] Having described the invention in detail, those skilled in theart will appreciate that, given the present disclosure, modificationsmay be made to the invention without departing from the spirit of theinventive concept described herein. Therefore, it is not intended thatthe scope of the invention be limited to the specific and preferredembodiments illustrated and described.

We claim: 1) An etching solution for the planarization of a Cu/Ta/TaNsurface comprising: a) an oxidizing reactant selected from the groupconsisting of H₂O₂, HNO₃ and mixtures thereof; and, b) a co-reactant isselected from the group consisting of H₃PO₄, H₂SO₄, HNO₃, oxalic acid,acetic acid, organic acids and mixtures thereof; and, c) other additivesselected from the group consisting of selected from the group consistingof HCl, aliphatic alcohols, butylated hydroxytoluene, Agidol-2,2,6-di-tert-butyl-4[(dimethylamino)methyl]phenol,2,6-di-tert-4N,N-dimethylaminomethylphenol, borax, ethylene glycol,ZnSO₄, methanol, propanol, poly(oxyethylene)lauryl ether, malic acid,HOOC(CX₂)_(n)COOH wherein X═OH, amine, H and n=1-4), 3% tartaric acid,1% ethylene glycol, 1,2,4-triazole, 1,2,3-triazole, tetrazole, nonionicsurfactant, ethanol, triflouroethanol, SiF₆, organic salt surfactant,polyvinyl alcohol, diphenylsulfamic acid, sodium oxalate, benzotriazole,sodium lignosulfonate, glycol, gelatin carboxymethylcellulose, amines,heavy metal salts, salts of Cu and Ta, KCl, CuCl₂, SnCl₂, propyleneglycol, 2-ethyl-hexylamine, copper carbonate, low molecular weightalcohols, glycols, phenols, aliphatic alcohols, polyvinylalcohols,anionic surfactants, cationic surfactants, fluorocarbon-basedsurfactants, nonionic surfactants having the properties ofpreferentially adhering to certain materials, modifying thereby thechemical reactivity where so adhered, polyvinyl alcohol solutionstabalizers and species inhibiting spontaneous decomposition ofoxidizing agents, wetting agents and mixtures thereof. 2) An etchingsolution as in claim 1 further comprising a species selected from thegroup consisting of CuCl, FeCl, FeCl₃, and mixtures thereof. 3) Anetching solution for the planarization of a Cu/Ta/TaN surface comprisingspecies selected from the group consisting of NaClO₃, FeNO₃, (NH₄)₂S₂O₈,CuNH₄Cl₃, Na₂S₂O₈, K₂S₂O₅, NH₄F, CuSO₄, NH₄OH, sodium EDTA salt ofwetting agent and mixtures thereof. 4) An etching solution for theplanarization of a Cu/Ta/TaN surface comprising species selected fromthe group consisting of, (NH₄)₂S₂O₈, KOH, NH₄OH, H₂O₂, Cu(NO₃)₂ andmixtures thereof. 5) An etching solution for the planarization of aCu/Ta/TaN surface comprising species selected from the group consistingof HF, HNO₃, H₂O₂, H₂SO₄, lactic acid and mixtures thereof. 6) Anetching solution for the planarization of a Cu/Ta/TaN surface comprisingspecies selected from the group consisting of, NaOH, KOH, NH₄OH, H₂O₂,and mixtures thereof. 7) An etching solution for the planarization of aCu/Ta/TaN surface comprising: EDTA, NH₄OH, H₂O₂, in aqueous solution. 8)An etching solution for the planarization of a Cu/Ta/TaN surfacecomprising: citric acid, erythorbic acid, triethanolamine, in aqueoussolution. 9) An etching solution for the planarization of a Cu/Ta/TaNsurface comprising: trisodium citrate, triethanolamine, sodium nitrate,in aqueous solution. 10) An etching solution for the planarization of aCu/Ta/TaN surface comprising: H₂SO₄, H₂O₂, sodium molybdate,phenolsulfonic acid, in aqueous solution. 11) An etching solution forthe planarization of a Cu/Ta/TaN surface comprising: mineral acid,molybdenum salt. 12) An etching solution for the planarization of aCu/Ta/TaN surface as in claim 1 further comprising abrasive particlesselected from the group consisting SiO₂, Al₂O₃ metallic and solidelemental particles, polymer particles, oxides, carbides, fluorides,carbonates, borides, nitrides, hydroxides of Al, Ag, Au, Ca, Ce, Cr, Cu,Fe, Gd, Ge, La, In, Hf, Mn, Mg, Ni, Nd, Pb, Pt, P, Sb, Sc, Sn, Tb, Ti,Ta, Th, Y, W, Zn, Zr, and mixtures thereof. 13) An etching solution asin claim 12 wherein said abrasive particles are coated. 14) An etchingsolution as in claim 13 wherein said coating is a chemically activespecies. 15) An etching solution as in claim 12 wherein said coating isCeO₂. 16) An etching solution as in claim 12 wherein said particles areproduced by the sol method. 17) An etching solution as in claim 12wherein said particles have a range of sizes from approximately 4nanometers to approximately 5 micrometers. 18) An etching solution as inclaim 12 wherein said particles have a size less than approximately 5micrometers. 19) An etching solution for the planarization of aCu/Ta/TaN surface comprising a) from approximately 50 parts by volume toapproximately 70 parts by volume of concentrated aqueous H₃PO₄; and b)from approximately 24 parts by volume to approximately 40 parts byvolume of concentrated aqueous acetic acid; and, c) from approximately 3parts by volume to approximately 10 parts by volume of concentratedaqueous HNO₃. 20) An etching solution as in claim 19 further comprisingfrom approximately 1 part by volume to approximately 15 parts by volumeof concentrated aqueous HF. 21) An etching solution for theplanarization of a Cu/Ta/TaN surface comprising an aqueous solution ofapproximately 42% by volume of sulfuric acid, approximately 8% by volumenitric acid and approximately 0.5% by volume hydrochloric acid.